DROWN vulnerability gives organizations a sinking feeling

An international team of researchers has uncovered an attack that can compromise encrypted network traffic in a matter of hours.

The DROWN attack (Decrypting RSA with Obsolete and Weakened Encryption) is the latest in a long line of serious vulnerabilities reported in some of the essential crypto protocols people around the world rely on to secure everything from email and IM’s to online banking transactions. When these vulnerabilities are successfully exploited it gives an attacker the ability to capture data the users assumed was securely encrypted.

James Maude, Senior Security Engineer at Avecto commented:

“This particular vulnerability is targeting a weakness in the SSLv2 protocol which was deprecated in 1996. Despite this, the now 21 year old protocol is still used on up to one third of all HTTPS servers. The problem is many organisations have a set and forget policy or simply use outdated tools that don’t disable SSLv2 by default which leads to these weak protocols still being available. In this case SSLv2 is used to undermine the much more secure TLS protocol by using SSLv2 to extract the key. Many had previously worked on the assumption that having a weak protocol available was not an issue if the client never used it, however this and other recent attacks have proved this wrong.

"Recent research has shown how attackers can exploit weak ciphers and protocols by forcing a user to downgrade their connection to one of the less secure ones available or use exploits in OpenSSL like CVE-2015-3197 which allows an attacker to use weak ciphers that were thought to be disabled on the server. As with so many things in IT security the issues come from not maintaining up to date patched software and not following industry best practices. Often organizations focus purely on their public website when it comes to issues like this not realising that any HTTPS mail servers or software that supports SSLv2 could also be vulnerable. Organizations that reuse certificates across web and email servers should be especially concerned as if one is vulnerable the attacker can use this to exploit others.

“The best advice is to update your crypto libraries as soon as possible and ensure they are configured in line with best practice to removes deprecated and weak protocols and ciphers.”